Gnumeric was such a good clone of Excel, it even duplicated bugs in Excel's statistical functions. These errors were brought to the attention of the Gnumeric development team, who have fixed most of the math bugs. Even with a decade's worth of releases, Excel's statistical bugs persist.
If statistical accuracy is important to you, and you use spreadsheets, you should probably be using Gnumeric now. Read the paper for more details, and you know WTF a Poisson Distribution is.
